Electrospinning has been recognized as one of the most efficient techniques for producing non-woven fiber webs on the order of several hundreds of nanometers by electrically charging a suspended droplet of polymer solution with/without inorganic precursors or melt. Various types of materials with a high degree of porosity, a large surface area, superior mechanical properties and modified surface functionalities, can be electrospun into nanofiber structures.

Scattering-type scanning near-field optical microscopy (s-SNOM) has become a powerful tool to directly visualize the optical properties of solids on ultrasmall length scales, far beyond the diffraction limit of light. Using this technology fascinating phenomena like propagating phonon [1] or plasmon-polaritons [2,3], the formation of metallic puddles in vanadium dioxide [4], and even mid-infrared absorption bands of single molecules [5] could be visualize with <10nm spatial resolution.